Vapour lead-through system for a rotary evaporator, and a rotary evaporator

ABSTRACT

A vapour lead-through system for a rotary evaporator with a rotatable evaporator vessel ( 5 ) and a stationary cooler ( 7 ) consists of a vapour lead-through tube ( 6 ) and a connection piece ( 8 ). The vapour lead-through tube ( 6 ) is on the cooler-side mounted in a stationary seal ( 9 ). On the evaporator-side end the vapour lead-through tube ( 6 ) is connected to the connection piece ( 8 ) in a manner such that the axis (A) of the vapour lead-through tube ( 6 ) is movable with respect to the axis (A′) of the connection piece ( 8 ).

[0001] The invention relates to a vapour lead-through system for a rotary evaporator and to a rotary evaporator, with the features of the preamble of the independent patent claims.

[0002] Such vapour lead-through systems are already known. Thereby vapour lead-through system connected to the evaporator flask is surrounded and driven by a drive part. The vapour lead-through system is led via a seal into or onto a static cooler. With this the seals on account of the rotation are mechanically loaded and must be regularly replaced in order to guarantee the functioning and operational safety.

[0003] EP 504 099 shows an at least two-part vapour lead-through tube with which the end-faces of the static part as well as the rotatable part in contact with the drive part are formed as sealing surfaces, wherein materials which are as low-wear and as resistant as possible such as plastic materials are combined with ceramic or glass materials.

[0004] A disadvantage of the known vapour lead-through systems lies in the fact that the rotatable vapour lead-through tube is in direct contact with the drive part. The movement of the drive part which is in no way exactly concentric, leads to eccentric forces which act directly on the vapour lead-through tube. As a result mechanical loading of the seals occurs.

[0005] DE 15 19 744 shows a vapour lead-through tube connected to the drive part, with a seal which is rigidly held by the radial extension of a flange but is held in a radially compensating manner between the sealing surfaces of the cooler and drive part.

[0006] The radial sliding movement arising by way of this leads to a corresponding mechanical loading.

[0007] It is the object of the invention to avoid the disadvantages of the prior art, in particular thus to provide a vapour-lead-through system and a rotary evaporator with which eccentric forces on the seals are minimised and the wear resistance is increased,

[0008] According to the invention this object is achieved with a vapour lead-through system and with a rotary evaporator according to the characterising features of the independent patent claims.

[0009] By way of the subdivision of the vapour lead-through into a connection piece which is drivable with the drive part and connected or connectable to the evaporator vessel, and into a vapour lead-through tube rotatably mounted in a seal stationary with respect to a cooler it is achieved that forces arising by way of the drive part act mainly upon the connection piece and where appropriate only on the evaporator-side end of the vapour lead-through tube. The transmission of eccentric forces from the connection piece in connection with the drive part onto the seal stationary with respect to the cooler is minimised in that the vapour lead-through tube is connected to the connection piece in a manner such that its axis is movable with respect to the axis of the connection piece. The vapour lead-through tube with respect to the stationary seal is to a certain extent decoupled from the drive piece.

[0010] It is particularly advantageous when the stationary seal bears sealingly on the outer wall of the vapour lead-through tube and has been manufactured in such a way and material that even under a heat and chemical effect it does not change in shape or pre-tension. This modified material, for example PTFE permits the stationary seal also during the operation to bear optimally at all times on the vapour lead-through tube. The independence of the vapour lead-through tube on the evaporator-side end, of an eccentric movement of the drive part permits the application of such materials in the stationary seal since these also with eccentric movement of the drive part are only minimally mechanically loaded.

[0011] A stationary seal of an inert, friction-modified plastic, in particular PTFE, is particularly suitable for this. By way of the restoring properties of this PTFE the reversible deformability is ensured. Furthermore PTFE is chemically resistant with regard to solvent-containing vapours and is friction-modifiable, by which means the mechanical loading by way of friction may be minimised.

[0012] Of course also other materials with suitable properties are conceivable.

[0013] It is particularly advantageous when the seal is held in a base body or an inert plastic, in particular PTFE.

[0014] A mounting of the stationary seal in a base body of an inert plastic has several advantages. The base body may likewise assume sealing functions. In particular the cooler-side end-face of the base body may be arranged such that it bears sealingly on a cooler-side connection piece.

[0015] As particularly suitable has shown to be a base body of an inert plastic, in particular PTFE, since various regions of the base body may be directly exposed to the solvent-containing vapours.

[0016] According to a preferred embodiment one design of the stationary seal as an annular body with a deformable lip is particularly favourable. Thereby the deformable lip assumes the sealing function and the annular body acts in a stabilising manner.

[0017] Additional stability of the stationary seal is achieved by a first ring, in particular a steel ring on the outer periphery of the base body and/or a second ring, in particular a steel ring, in the seal. Conceivable are also other materials of steel which sufficiently stabilise the seal.

[0018] The vapour lead-through tube may on the evaporator-side end be mounted in a seal whereby the outer wall of the vapour lead-through tube sealingly bears on the inner side of the seal.

[0019] Particularly suitable is an evaporator-side seal which in cross section is formed V-shaped. The inner and outer limbs of such a seal may be formed as sealing surfaces.

[0020] It is particularly advantageous when the evaproator-side seal on its outer side comprises a spherical surface and the connection piece comprises a taper-ground joint, wherein the spherical surface of the seal whilst forming a ball joint lies sealingly in the taper-ground joint: of the connection piece. The ball joint permits in a particularly simple manner a movability of the evaportaor-side seal to the connection piece and thus a compensation of an eccentric movement of the connection piece at the evaporator-side end of the vapour lead-through tube. Eccentric forces which occur at the connection piece being in connection with the drive part are by way of this particularly effectively compensated. Conceivable is also a kinematic reversal so that the vapour lead-through tube via a taper-ground joint bears on the outer side of the evaporator-side seal and the connection piece comprises a conical surface which is in contact with the inner side of the seal.

[0021] Particularly proven to be successful is when the evaporator-side seal consists of an inert plastic, in particular PTFE, since this material has the required thermal resistance and solvent resistance. Conceivable however are also all other materials which have the mentioned properties

[0022] An O-ring within the evaporator-side seal may in particularly be advantageous for the stability of the sealing arrangement. Particularly suitable is a rubber ring since it has the necessary elasticity in order to dampen radial forces in the ball joint.

[0023] By way of a fixation in the axial direction on the evaporator-side end of the vapour lead-through tube a displacement of the vapour lead-through tube in the axial direction, in particular with a manipulation on the apparatus, may be avoided. The fixation may be particularly simply realised when the vapour lead-through tube comprises a flange which is latchable on a retaining element on the drive part, e.g. in a groove with an O-ring. Conceivable however are also other realisation forms of the fixation in the axial direction.

[0024] The invention is hereinafter decribed in more detail in embodiment examples by way of the drawings. There are shown in:

[0025]FIG. 1 a perspective representation of a rotary evaporator,

[0026]FIG. 2 a longitudinal section through an embodiment example of a vapour lead-through system with the features of the invention,

[0027]FIG. 3 an enlarged representation of the cooler-side seal according to FIG. 2 and

[0028]FIG. 4 an enlarged representation of the evaporator-side seal according to FIG. 2.

[0029]FIG. 1 shows a rotary evaporator 1 with a stand 2 on which there is fastened a motor 3 which via a drive part 4 drives an evaporator vessel 5. Through the drive part 4 as a vapour lead-through arrangement there runs a vapour lead-through tube 6 (FIG. 2), through which the vapour rising from the evaporator vessel 5 is led into EL cooler 7. With this the cooler 7 in a manner known per se is stationarily fastened.

[0030]FIG. 2 shows the arrangement of the vapour lead-through system. On the evaporator-side end 23 there is located a connection piece 8 which in the known manner is connected to an evaporator vessel 5. On the end facing the drive part 4, the connection piece 8 with its inner surface 27 which is formed as a taper-ground joint 25 bears on the outer limbs 29 of a seal 15 designed V-shaped in cross section (see FIG. 4). The outer surface 28 of the connection piece 8 is in contact with the drive part 4 so that the connection piece 8 is rotatable.

[0031] The vapour lead-through tube 6 is led through the drive part 4. On the evaporator-side end 23 the vapour lead-through tube 6 comprises a groove 19 into which the seal 15 v-shaped in cross section may be latched so that the vapour lead-through tube 6 is sealingly in connection with the inner limbs 30 of the seal 15. The V-shaped seal 15 comprises a conical surface 26 so that the vapour lead-through tube 6 is connected to the seal 15 and the connection piece 8 in the manner of a ball joint which is held together by forces in the axial direction (see FIG. 4). By way of the non-positive fit resulting with such an arrangement it is achieved that the vapour lead-through tube 6 by way of the connection piece 8 being in connnection with the drive part 4 is set into a rotational movement.

[0032] Additionally the vapour lead-through tube 6 on the evaporator-side end 23 has a flange 17 which is latchable in a deepening 18 of the drive part 4. Into the deepening 18 there is applied a ring 16. By way of this a fixation of the vapour lead-through tube 6 in the axial direction is guaranteed. The vapour lead-through tube 6 from the evaportator-side end 23 is led through the drive part 4 into a stationary seal 9 on the cooler-side end 24 without at the same time the vapour lead-through tube 6 being in direct contact with the drive part 4. By way of this arrangement it is achieved that the vapour lead-through tube 6 is relatively movable with respect to the axis A of the drive part 4. Eccentric forces which are transmitted via the connection piece 8 onto the vapour lead-through tube 6 may thus be compensated by a movement shown in FIG. 2 as position A″ and be kept away from the stationary seal 9. Between the outer wall 31 and the inner surface 32 of the drive part 4 there is provided an annular gap 33 which permits this compensation movement.

[0033]FIG. 3 shows the cooler-side stationary seal 9. This bears sealingly on the outer wall 31 of the vapour lead-through tube 6 and is reversibly deformable under a heat effect. The actual sealing function is thereby assumed by a deformable lip 12 whilst the annular body 11 of the stationary seal 9 serves for the mounting. To have particularly proven itself is a stationary seal 9 of an inert, friction-modified plastic, in particular PTFE which has at its disposal the necessary restoring properties. The stationary seal 9 is held by a base body 10 and is stabilised by way of a first ring 13 on the outer circumference and a second ring 14 in the inside of the stationary seal 9. The base body 10 comprises a circumferential deepening 21 in which the vapour lead-through tube 6 is applied. The base body 10 has an end face 22 which bears on a sealing surface 34 of the cooler. By way of the arrangement shown in FIG. 3 parts of the base body lo are directly in contact with the solvent containing vapours. Particularly suitable is therefore a base body 10 of an inert plastic, in particularly PTFE. The design of the base body 10 shown in FIG. 3 additionally acts sealingly with respect to the cooler-side back flow. For the vapour lead-through tube 6 and the cooler-side connection piece glass is particularly well suited.

[0034] Between the cooler-side connection piece and the base body 10 of the seal 9 no rotation takes place. The vapour lead-through tube 6 is in contrast rotatable with respect to the seal 9.

[0035]FIG. 4 shows the evaporator-side seal 15 whose outer limbs 29 sealingly bear on the inner surface 27 of the connection piece 8, which is designed as a taper-ground joint 25. The inner limbs 30 of the seal 15 bear sealingly on the outer surface 31 of the vapour lead-through tube 6. The seal 15 may additionally be stabilised by an O-ring 20. 

1. A vapour lead-through system for a rotary evaporator (1) with a rotatable evaporator vessel (5) and a stationary cooler (7), with a vapour lead-through which connects the evaporator vessel (5) to the cooler (7) and with a drive part (4) for rotating the evaporator vessel (5), chracterised in that the vapour lead-through comprises a connection piece (8) and a vapour lead-trough tube (6) whereby said connection piece (8) is drivable with the drive part (4) and is connected or connectable to the evaporated vessel (5), and whereby said vapour lead-through tube (6) at its coolerside end (24) is mounted in a seal (9) which is stationary with respect to the cooler (7), and whereby the vapour lead-through tube (6) is connected to the connection piece (8) in a manner such that the axis (A) of the vapour lead-through tube (6) is movable with respect to the axis (A′) of the connection piece (8).
 2. A vapour lead-through system according to claim 1 , whereby said seal (9) bears sealingly on the outer wall (31) of the vapour lead-through tube (6) and whereby said seal (9) under a heat effect is reversibly deformable.
 3. A vapour lead-through system according to claim 1 wherein said seal (9) consists of an inert, friction-modified plastic, in particular PTFE.
 4. A vapour lead-through system according to claim 1 wherein said seal (9) is held in a base body (10) of an inert plastic, in particular PTFE.
 5. A vapour lead-through system according to claim 4 , wherein said base body (10) bears sealingly on a connection piece of the cooler (7).
 6. A vapour lead-through system according to one of the claim 1 , wherein said seal (9) comprises an annular body (11) and a deformable lip (12).
 7. A vapour lead-through system according to claim 1 wherein said seal (9) comprises a first ring (13) in particular a steel ring, on the outer circumference of the base body (10) and/or a second ring (14), in particular a steel ring, within the seal (9), which stabilise the seal.
 8. A vapour lead-through tube according to claim 1 , wherein said vapour lead-through tube (6) at the evaporator-side end (23) is mounted in a seal (15) in such a manner that the outer wall (31) of the vapour lead-through tube (6) sealingly bears on the inner side of the seal (15).
 9. A vapour lead-through system according to claim 8 , wherein said evaporator-side seal (15) in cross section is V-shaped.
 10. A vapour lead-through system according to claim 8 , wherein said evaporator-side seal (15) by way of axial forces is sealingly connected and in the circumferential direction connected with a non-positive fit, to the connection piece (8).
 11. A vapour lead-through system according to one of the claim 8 , wherein said evaporator-side seal (15) on its outer side comprises a spherical surface (26) and the connection piece (8) on its inner side a taper-ground joint (25), wherein the spherical surface (26) of the seal (15) whilst forming a ball joint sealingly lies in the taper-ground joint (25) of the connection piece (8).
 12. A vapour lead-through system according to claim 8 , wherein said seal (15) on the evaporator-side end (23) of the vapour lead-through tube (6) consists of an inert plastic, in particular PTFE.
 13. A vapour lead-through system according to claim 8 , wherein said evaporator side seal (15) in the inside comprises an O-ring (20), in particular of rubber.
 14. A vapour lead-through system according to claim 1 , wherein said vapour lead-through tube (6) in particular at the evaporator side end (23) comprises a fixation in the axial direction.
 15. A vapour lead-through system according to claim 14 , wherein said vapour lead-through tube (6) comprises a flange (17) which is latchable in a deepening (18) of the drive part (4).
 16. A rotary evaporator (1) with a rotatable evaporator vessel (5) and a stationary cooler (7), with a vapour lead-through system which connects the evaporator vessel (5) to the cooler (7) and with a drive part (4) for rotating the evaporator vessel (5), characterised in that the vapour lead-through system is designed according to claim 1 . 